Supercharger for aeroplane engines



Dec. 28 1926. 1,612,314

V. U. D. PIERCE I SUPERCHARGER FOR AEROPLAN E ENGINES filed June 25.1921 2 Shets-Sheet 1 Dec. 28, 1926. 1,612,314

' v V. U. D. PIERCE SUPERCHARGER FOR AEROPLANE ENGINES Filed June 25,1921 2 Sheets-Sheet 1 [117. Pierce Patented Dec. 28, 1926.

STATES I). PIERCE, 0F WASHING-TON,

VINTON U.

DISTRICT OF COLUMBIA; JOSIAH PIERCE EXECU'IOR OF SAID V. U. I PIERCE,DECEASED.

snrnnonnnenn Fon- AnnorLnnn ENGINES.

Application filed June 25,

This invention relates to means whereby the engine of an aeroplane canbe forced to operate under sea level conditions and therefore delivernormal horsepower irrespective of the altitude at which the enginehappens to be, and particularly to those supercharge s in whichreciprocating piston pumps are used for delivering into each cylinder agreater weight of air than ordinarily would be drawn in as the piston ofthe engine moves downward on its suction stroke.

is is well known, the air becomes thinner the hi her the altitude, andas a consequence an engine which has a certain power at sea level hasits power decreased as its altitude increases. To avoid this manydifferent tour" of superchargers have been devised c f ting to force thecharge into the cylinder oi the engine upon the suction stroke so as tocompensate for decreased air pressure.

One of the main ditliculties incident to supercharging is to providemeans whereby the supercharging can be easily and delicately regulatedto compensate for differences in air pressure at various altitudes, andit is common practice to hold the supercharger mechanism out ofoperation until the engine has reached a certain altitude, as forinstance ten or fifteen thousand feet, and then the supercharger is putin operation and delivers its maximum charge.

The general object of this present invention is to provide asupercharger for the purpose described which delivers air through thecarburetor oi the engine, the carbureter being provided with its own airintake for use at sea level or low altitudes, and pro-' vide meanswhereby the air delivered from the supercharger may either be alldirected through the carbureter and so into the cylinders of the engine,or whereby a portion 01" the air passing from the supercharger may passto the engine and a portion of the air be relieved.

A further object is to provide a valve for the purpose of controllingthe passage of air to the engine which shall be of very simple yeteffective construction and which may be easily regulated to secure anydesired press ire of air within the cylinders within range of themechanism.

A further object is to provide a construction of such simplicity that itmay be dis- 1921. Serial No. 480,440.

posed between the engine bank and the propeller oi the engine and whichincludes reciprocating pumps having the cylinders of such proportionsand pistons operating at such speeds that one cylinder of the pump willtake care of and furnish air for a plurality of engine cylinders.

Another object is to provide a construction or this kind wherein thepump cylinder has a capacity twice that of any en 'ine cylinder and sogeared to the crank shart of the engine that the piston of the pump willreciprocate twice as fast as the pistons ot' the engine, thus permittingone cylinder of the pumpto deliver air sufficient for a plurality ofcylinders.

Still another object is to provide a maximum inlet for the air to thepumping cylinder and a maximum outlet for the air to the cylinders ofthe engine.

Other objects will appear in the course oi the following description.

My invention is illustrated in the accompanying drawings, wherein Figure1 is a front elevation 01 an aeroplane engine provided with my improvedsupercharger Figure 2 is a side elevation of the engine with a portionof the propeller of the aero plane, the crank case of the superchargerbeing broken away;

Figure 3 is a fragmentary sectional view through the upper end of one ofthe pump ing cylinders showing the inlet and outlet valves thereof, theoutlet pipe leading from the pumping cylinder being also broken away toshow the interior ot the relief valve casing;

Figure is an enlarged top plan view of the inlet and outlet valvecasings of the pump showing the manner in which the valves are operatedby the cam shaft of the engine;

Figure 5 is an. outside face view of the valve and the frame supportingthe valve;

Figure 6 is an end elevation of an aeroplane engine with a singlepumping cylinder applied thereto;

Figure 7 is a longitudinal sectional view throughthe pumping cylindershowing the valves, the engine being shown in elevation;

Figure 8 is a top plan view of the pumping cylinder and its alliedparts;

Figure 9 is a horizontal sectional view through the crankcaseof thepumping. cylinder showing the lower set of inlet and exhaust valves, thesection being taken on the line 99 of Figure 7 looking in the directionof the arrows.

In the drawings, 1 have illustrated a Hispano-suiza aeroplane engine andhave illustrated my invention as applied thereto, but this is purely forillustrative purposes, and it will be understood that the invention maybe equally well applied to any other make of engine and that I do notwish to be limited to the use of my invention applied to a ll-typeengine.

In these drawings, A designates the crank case of the engine, 13 theengine block, C the intake manifold, and l) the carburetor which has anair inlet opening at any desired point, as for instance a the end (Z,and which is used under ordinary circumstances. Extending through thecrank case is the usual crank shaft E which is connected to thepropeller F. All of these parts are of any suitable or usualconstruction.

Mounted upon the engine block or crank case between the engine block andthe propeller are two outwardly divergent pumping cylinders 10. Theseare illustrated in Figure 1 as single acting pumping cylinders, andoperating within each cylinder 10 is the usual trunk piston ll. Thesepistons are connected to the downwardly converging piston rods 12, whichin turn are connected to a crank 13 disposed in the housing 14 which iscommon to both of the cylinders 10, this crank being operativelyconnected to a crank shaft 15 illustrated as carrying upon it a sprocketwheel 16 driven by a sprocket chain 17 from a sprocket wheel 18 mountedupon the crank shaft E of the motor. These sprocket wheels 16 and 18 andthe sprocket chains 17 are contained within a housing 19. Any othersuitable gearing may be used, however. It will be noted that theproportions of the sprocket gears and gear wheels 16 and 18 are suchthat the shaft 15 is driven at twice the speed of the shaft The housing1% as illustrated rests upon and is bolted to the extremity of the crankcase A, and the housing is triangular in side elevation so as to.provide two faces extending in an upwardly convergent relation, these.tacos supporting and being bolted to the flanged ends of the cylinders10. The outer ends of the cylinders 10 are formed with relativelyelongated intake ports 20 which open into the chamber 21 which extendstransversely across the upper end oi the cylinder 10, illustrated inFigure 3, this chamber having an intake valve seat 22 and an outletvalve seat 22*, the middle portion of the chamber being formed toprovide guides for the stems of valves 23 and Preferably there are twointake valves 23'a11d two outlet valves 24, these valves bein; held totheir seats by springs 25 and being positively opened by cams on camshafts 27 driven from the main cam shaft 26 of the engine. Where fourvalves are used, two intake valves and two outlet valves as illustrated,the cam shalt 26 of the engine is provided with a gear wheel 26 whichmeshes with pinions 27 mounted on cam shafts 27, there being a cam shaft27 for each pair of inlet and outlet valves. These cam shafts 27 carryon them the double cams 2S and 29 so formed that one rotation of eachshaft 2? will give two reciprocations to the valve stems 30 of thevalves 23 and 24. Gt course, the cams 29 are set reversely to the cams23, that is in quartering relation to these cams so that when the inletvalves 23 are opened, the outlet valve 24; will be closed, and viceversa. It will be unnerstood, of course, that this is the gearing usedwhere a single acting pump is to' deliver a charge or air for tourcylinders, and 1 do not wish to be limited to the use of four valves asillustrated but these four valves are used simply for the purpose ofsecuring ample inlet port area and ample outlet port area. Obviously agreater or less number of valves may be used and these valves may beactuated in other ways, depending upon the character of the engine andother service factors.

Leading from each chamber 21 is a duct or pipe 31 which leads into acommon chamber 32, which at the end 33 is connected to the carbureter Dat the open end d, this end 33 formin an outlet port communicating withthe carburetor and supplying air thereto. The casing 32 is also formedwith a relief port- 34, and disposed within the bottom of the chamber 32and illustrated as rotatably mounted on the walls thereof is a reliefvalve 35 having a plurality of racially disposed ports 36 and providedwith a valve operating arm The valve is pivoted upon a pintlc 38. Thisvalve, as will be obvious from Figure 5, may be shifted to entirelyclose the relier port 3% or may be shifted so as to be entirely open. vlhcn the valve is entirely closed, all of the air coming from the CO1press-or and compressing pump 10 is forced through the carburetor andinto that engine cylinder which is on its suction stroke. If: the reliefport be entirely open, the engine will only secure air at atmosphericpressure, and it will be obvious that if this valve be in anintermediate position, part of the air forced into the duct 31 will passinto the carbureter and part of the air will be relieved and thus itwill be obvious that by adjusting this valve 35, any desired amount ofair under pressure can be forced through the carbureter to compensatefor the thinness oi the air at any particular altitude and to securethrough the engine a supply of air equal to that which it would normallyrc quire at sea level,

lili) miners In the construction which I have illustrated, the cylindersl O'haVe a capacity twice that of any one of the cylinders F of theengine, and thus it will be seen that as the pistons 11 operate at twicethe speed of the pistons in the cylinders F, each pumping cylinder willprovide air under pressure for four cylinders, and thus the twocylinders illustrated will take care of an eightcylinder motor of all-type.

Attention is called to the fact that with my construction there is noback pressure due to using the exhaust as a means for driving an aircompressing pump, and furthermore that the cylinders of the pump aredisposed between the engine bank 13 and the propeller F, and that such adisposition of the pump makes it possible to apply this pump toaeroplane engines without in any way changing the form of the engine andwithout disturbing in any way the balance of the engine or of theaeroplane.

One of the important features of my invention resides in the fact thatwith this de vice, while it is possible to compensate by its use for thegradual thinning of the air as the machine rises, yet there is no dangerof preignition. Superchargers known to me are only brought into use at acertain altitude for the reason that if the pump-were used to its fullpower below the altitude for which it was designed, it would causepie-ignition, due to supercompression in the engine cylinders. lVith myconstruction, the pilot has at all times a very delicate and exactcontrol over the amount of supercharging air which is forced into theengine upon tne suction stroke thereof. There are no clutches to operateor other variable compression mechanism, the mechanism is extren'ielysimple and within standard practice, and the only controlling mechanismnecessary is the controlling valve and the means whereby it may beoperated, which means is under control of the pilot at all times andrequires no delicate manipulation.

t will be seen that the portion. 34 consti tutes in effect a chamberconnected at one end to a source of air under pressure and at theopposite end connected to the carburetor, and that the valve 35 and therelief port may be adjusted to an extent sufi'icient to permit theescape of excess air from the duct or chamber 31, and that the greaterthe open ing of the relief valve, the less the pressure aboveatmospheric pressure of air entering the carburetor, while when therelief port is entirely closed, the pressure of air passing through thecarbureter will be the same as the pressure of the air as it isdischarged from the compression pump.

While in Figures 1 to 5 l have illustrated twin single acting pumpsconnected to the two sets of cylinders of a \/type engine, in Figures 6to 9 I have illustrated a single pumping cylinder operatively connectedto two sets'of engine cylinders and constituting a double acting pump.In these figures, B designates the engine block and A the crank case ofthe engine, 1) designating the car-- bureter, C the'intake manifoldbranch leading from the carbureter on the middle line of the engine, andc the branches leading laterally from the branch C and connecting to theintake manifold c. all of these parts may be of any usual or suitableconstruction.

Disposed between the engine bank B and the propeller F mounted on thecrank shaft E is a double acting pump cylinder 'Ehis is shown as a fincooled cylinder. Within the cylinder is disposed a piston 40 connectedby the connecting rod ll to the crank 42 of a crank shaft 43 mounted insuitable bearings below the cylinder and driven by sprocket wheels asand 46 and chain 45, the wheels a l being mounted upon the crank shaft Eand the wheel 4:5 being unted upon the crank shaft 43, this gearidriving the crank shaft 43 at a speed twice that of the crank shaft E.The upper end of the cylinder 39 is shown as provided with an inlet hoodl7 having two inlet openings extending into the upper end of thecylinder 39 and controlled by two inlet valves 48, the stems l9 of whichreciprocate within tubular guides 50.

There are two inlet valves 51 in the upper end of the cylinder whosestems extend outward through a discharge pipe 52, these stems beingdesignated 53. The lower end of the cylinder is formed with a well 541:within which the crank a2 revolves, which well communicates with thelower end of the cylinder 39' and this well is provided, as illustratedin Figure 9, with two inlet ports 55 and two outlet ports 5(. The inletports are controlled by valves 57 having stems extending out throughsuitable bushings and the outlet ports are controlled by valves 58 whosestems extend outward through suitable bushings, all as illustrated inFigure 9.

For the purpose of operating the inlet valves 48 and the outlet valves51 in the upper end of the engine, I provide a rocker arm 59 (see Figure8) which at its forward end is branched or T-shaped so as to engage bothstems d9 of the valves 48. The rear end of this rocker arm is engaged bya vertically reciprocating rod 60, which rod extends downward verticallyjust behind the cylinder 39 and is: supported in suitable guides and isengaged by a cam 61 mounted upon the crank shaft 43 of the pump. Thestems 53 of the valves 51 are engaged by an approximately lJ-shapedrocker 62 pivoted at 63 and reciprocated by a longitudinally extendingrod G l which extends down between the cylinder 39 and the outlet pipeand is engaged by a cam 65 mounted upon the crank rod a3. These cams 61and 65 are, of course set reversely to each other so that the rods 60and 61 will be alternately raised. When these rods are raised, they willobviously depress each its own pair of valves. Thus the inlet valves 48will be opened alternately to the valves 51, the lower pair of inletvalves is operated by a transversely extending rock shaft 66 having amedially disposed, rearwardly extending arm 6'? which engages with acontact rod 68 mounted in a suitable guide and reciprocated by means ofa cam 69 on the crank shaft l3. The ends of the shaft 66 carry uponthem. the upwardly extending contact arms 70 which engage with the valvestems 71 of the valves 55. These valves are held closed by springs andare opened by the inward movement of the arms 70 due to the action ofthe cam 69. The outlet valves 58 a are also held closed by springs andare pthat the outlet valves 58 which control the outlet from the lowerend of the cylinder are opened. at the same time that the inlet valvesat the upper end of the cylinder open, while the cam 69 is so timed thatthe inlet valves for the lower end of the cylinder open when the outletvalves 51 for the upper end of the tylinder open. Thus while the valvesare opened for suction at one end of the cylinder, the outlet valves areopened for discharge at the other end of the cylinder, and vice versa.

A pipe or duct 76 extends'from the chambers on the outlet side of theseats 56, as illustrated in Figures '4" and 9, this branch pipe or duct76 opening into the duct or pipe It will thus be seen that a constantcurrent of air under pressure is being discharged at all times into thecarbureter unless the relief valve be fully opened to an extent wherethe pressure in excess of the atmospheric pressure is relieved. Therelief valve is designated 36 and its operating arm 37, as in Figures 1to 5. This relief valve operates in exactly the same manner asheretofore described.

This construction is in principle the same as described in Figures 1 to5 and only differs therefrom in that a single compression pump is usedand in that this compression pump is illustrated as a double acting pumpwhere the pumps heretofore described were single acting pumps; This formof mechanism tends to reduce weight by providing a single pumpingcylinder instead of twin pumping cylinders, this single pumping cylinderpumping air for both sets of engines. It is, however, slightly morecomplicated as regards its valve gear.

I claim The combination with an aeroplane engine of the V-type havingtwo sets of'cylinders disposed in divergent relation, a crank shaft, apropeller mounted upon the crank shaft, and a carbureter for both setsof cylinders, said carbureter having an inlet port, of tWo divergentlyrelated pumping cylinders disposed between the engine bank and thepropeller and above the crank shaft and having a capacity approximatelydouble that of any of said cylinders and having inlet ports and outletports, a housing disposed between the inner ends of the pumpingcylinders and common to both of said pumping cylinders, a crank shaftdisposed within the housing, pistons operating in the cylinders andoperatively connected to the last named crank shaft, an operativedriving connection between the first and last named crank shafts, valvescontrolling the inlet and outlet of air from said pumping cylinders,engine driven means for operating the said Valves, and a tubularconnection leading from the outlet of each pumping cylinder to thecarbureter port and having a relief port, and manually controlled meansfor opening or partly opening the relief port.

In testimony whereof I hereunto affix my signature.

VINTON U. D. PIERCE.

